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1. Search the forum. You can do this from the Advanced Search Page or from our Google Custom Search, which will search the entire PKP site. If you are encountering an error, we especially recommend searching the forum for said error.

2. Check the FAQ to see if your question or error has already been resolved.

3. Post a question, but please, only after trying the above two solutions. If it's a workflow or usability question you should probably post to the OJS Editorial Support and Discussion subforum; if you have a development question, try the OJS Development subforum.

Our OJS have been installed without Captcha and we have received some invalid users with invalid emails. I have removed these users and they no longer appear in the users lists.

The problem I have is that it looks like the emails of the removed users are still in the DB. So each time a new issue is published and the notification email is sent, I receive a bunch of Delivery Failure emails.

If I check for users with the problematic emails, I get none. So I am assuming the invalid emails of the removed users are still in the DB and OJS sends notifications to them.

Do you have any idea if my assumption is correct? Any idea how to prove the assumption is correct? And for the end: how to remove these invalid emails?

The only places that OJS stores email addresses are in the users table (the email column) or also in the notification_mail_list table, in newer versions of OJS. There is an email column there as well. Have a look in that table, if it exists.